JP6559115B2 - X-ray scattering reduction device for use with 2D and 3D mammography - Google Patents

Description

(Citation of related application)
This application was filed on March 13, 2014 as a PCT international application and claims priority to US Provisional Patent Application No. 61 / 790,336 (filed on March 15, 2013), which is incorporated herein in its entirety. Is hereby incorporated by reference.

(Field of Invention)
The present invention relates generally to x-ray imaging, and more specifically to an anti-scatter device and method for reducing x-ray scattering for chest imaging.

  X-ray mammography systems are widely used for chest imaging. More recently, advanced imaging systems based on tomosynthesis have been developed for use in screening for breast cancer and other lesions. The tomosynthesis system is a three-dimensional (3D) mammography system that enables high resolution chest imaging based on limited angular tomography at mammographic x-ray dose levels. In contrast to a typical two-dimensional (2D) mammography system, a tomosynthesis system acquires a series of X-ray projection images, and each projection image moves along a path, such as an arc, with the X-ray source covering the chest. As a result, different angular displacements are obtained. In contrast to conventional computed tomography (CT), tomosynthesis is typically based on projection images obtained with limited angular displacement of the x-ray source around the chest. Tomosynthesis reduces or eliminates the problems caused by tissue duplication and structural noise present in 2D mammography imaging. Digital chest tomosynthesis also offers the potential for reduced chest compression, improved diagnostic and screening accuracy, fewer rework, and 3D lesion localization.

  Scattered x-rays generally cause blurring in the x-ray image and degrade its image quality. Anti-scatter grids are typically used in conventional 2DX imaging systems by selectively blocking scattered X-rays such as Compton scattered X-rays while allowing the primary X-rays to reach the X-ray detector. , Reduce X-ray scattering. Thus, the anti-scatter grid improves image quality and tissue contrast by reducing the number of detected x-rays scattered by the tissue. Although anti-scatter grids have been developed for use in conventional X-ray imaging systems such as 2D mammography, there is a need for X-ray scatter reduction devices and methods that work with tomosynthesis imaging.

  Aspects and embodiments of the present disclosure are directed to providing systems and methods for reducing X-ray scattering for chest imaging, and more specifically for tomosynthesis imaging. An anti-scatter grid and an x-ray imaging system in which the anti-scatter grid is incorporated are disclosed. In various embodiments, an x-ray imaging system can have an anti-scatter grid configured in accordance with aspects disclosed herein and can operate in at least one of a 2D mammography mode and a (3D) tomosynthesis mode. It can be. The use of anti-scatter grids is particularly useful for imaging thick breasts, eg, breasts that are unevenly dense or very dense.

Various aspects, embodiments, and advantages are discussed in detail below. Embodiments disclosed herein may be combined with other embodiments in any manner consistent with at least one of the principles disclosed herein, such as “one embodiment”, “some References to "embodiments", "alternative embodiments", "various embodiments", "one embodiment" and the like are not necessarily mutually exclusive and the specific features, structures described It is intended to indicate that a feature or characteristic may be included in at least one embodiment. The appearances of such terms herein are not necessarily all referring to the same embodiment. Features and advantages discussed in connection with any one or more embodiments according to one or more aspects are not intended to be excluded from a similar role in any other embodiments or aspects.
For example, the present invention provides the following.
(Item 1)
An apparatus for reducing X-ray scattering, the apparatus comprising:
A motor,
An anti-scatter grid coupled to the motor;
With
The anti-scatter grid has a plurality of partition walls, and the anti-scatter grid is substantially parallel to the coronal surface of the object during imaging of the object using an X-ray imaging device. Configured to be positioned with respect to the X-ray imaging device so as to extend along a parallel direction;
The motor is configured to retract the anti-scatter grid out of field in a first mode of the X-ray imaging device, and the motor is configured to move the scattering in a second mode of the X-ray imaging device. An apparatus configured to move a prevention grid relative to a detector within the field of view.
(Item 2)
The apparatus of item 1, wherein each partition of the plurality of partitions is substantially linear.
(Item 3)
Item 2. The device of item 1, wherein the anti-scatter grid has a density of at least 70 partitions / cm.
(Item 4)
4. The apparatus according to item 1 or 3, wherein each partition of the plurality of partitions is a thin strip having a length extending along a direction substantially parallel to the coronal surface of the object.
(Item 5)
4. The apparatus according to item 1 or 3, wherein the plurality of partition walls are arranged in a parallel configuration.
(Item 6)
4. The apparatus according to item 1 or 3, wherein the plurality of partitions are arranged in a focusing configuration, and the plurality of partitions are directed to the focal point of the X-ray source.
(Item 7)
The apparatus according to item 1, wherein the X-ray imaging device is a tomosynthesis imaging device.
(Item 8)
The apparatus of item 7, wherein the X-ray imaging device is configured to operate in a 2D mammography mode and a 3D tomosynthesis mode.
(Item 9)
The anti-scatter grid is further configured to move along a first direction substantially parallel to the sagittal plane of the object during imaging of the object using the X-ray imaging device. The apparatus according to item 1.
(Item 10)
The anti-scatter grid is further configured to move along a second direction substantially parallel to the coronal plane of the object during imaging of the object using the X-ray imaging device. The apparatus according to 1, 3, or 9.
(Item 11)
The anti-scatter grid follows and is effective for reducing moiré patterns in the resulting image during imaging of the object using the X-ray imaging device operating in tomosynthesis mode. The apparatus of item 1, further configured to move at a speed.
(Item 12)
12. The apparatus of item 11, wherein the anti-scatter grid is further configured to move along the trajectory during each exposure of a plurality of tomosynthesis exposures.
(Item 13)
13. Apparatus according to item 11 or 12, wherein the anti-scatter grid has a density of at least 70 partitions / cm to limit the distance of movement required to reduce the moire pattern.
(Item 14)
A motor coupled to the anti-scatter grid, the motor configured to move the anti-scatter grid during imaging of the subject's chest using the X-ray imaging device operating in a tomosynthesis mode; The apparatus according to item 1, wherein:
(Item 15)
Item 15. The apparatus of item 14, wherein the motor is one of a stepper motor, a servo motor, a linear motor, a voice coil, and a piezoelectric motor.
(Item 16)
The motor moves the anti-scatter grid along a first direction substantially parallel to the sagittal plane of the object during imaging of the chest using the X-ray imaging device operating in the tomosynthesis mode. Item 15. The device of item 14, further configured to move.
(Item 17)
15. The apparatus of item 14, wherein the motor is further configured to move the anti-scatter grid with a velocity profile that is one of a trapezoidal profile and a sinusoidal profile.
(Item 18)
Item 4. The device of item 1 or 3, wherein the anti-scatter grid is further configured to be retractable.
(Item 19)
An apparatus configured to operate in a tomosynthesis mode for imaging of a subject's chest, the apparatus comprising:
A motor,
An X-ray source configured to move for imaging in the tomosynthesis mode;
An X-ray detector;
A platform configured to position a chest between the x-ray source and the x-ray detector;
An anti-scatter grid disposed between the platform and the X-ray detector;
With
The anti-scatter grid has a plurality of partition walls, and each partition wall of the plurality of partition walls has a length extending along a direction substantially parallel to the coronal surface of the object,
The motor is configured to retract the anti-scatter grid out of the field of view in a first mode of the device, and the motor moves the anti-scatter grid to the field of view in a second mode of the device. And wherein the second mode is the tomosynthesis mode.
(Item 20)
Item 20. The apparatus of item 19, wherein the X-ray detector is configured to move in a reciprocal direction with respect to movement of the X-ray source during imaging in the tomosynthesis mode.
(Item 21)
21. The apparatus of item 20, wherein the anti-scatter grid is coupled to the X-ray detector, whereby the anti-scatter grid moves with the X-ray detector during imaging in the tomosynthesis mode.
(Item 22)
20. The apparatus of item 19, wherein the anti-scatter grid is configured to move along a first direction substantially parallel to the sagittal plane of the object during imaging in the tomosynthesis mode.
(Item 23)
24. The apparatus of item 22, wherein the anti-scatter grid is further configured to move along a second direction substantially parallel to the coronal plane of the object during imaging in the tomosynthesis mode.
(Item 24)
The anti-scatter grid is further configured to move along and at a speed effective for reducing moiré patterns in the resulting image during imaging in the tomosynthesis mode. The apparatus according to item 19.
(Item 25)
25. The apparatus of item 24, wherein the anti-scatter grid has a density of at least 70 septa / cm to limit the distance of motion required to reduce the moire pattern.
(Item 26)
25. The apparatus of item 24, wherein the anti-scatter grid is further configured to move along the trajectory during each exposure of a plurality of tomosynthesis exposures.
(Item 27)
Item 20. The apparatus of item 19, wherein the motor is one of a stepper motor, a servo motor, a linear motor, a voice coil, and a piezoelectric motor.
(Item 28)
28. The apparatus of item 27, wherein the motor is further configured to move the anti-scatter grid with a velocity profile that is one of a trapezoidal profile and a sinusoidal profile.
(Item 29)
29. Apparatus according to any of items 20 to 28, further configured to operate in 2D mammography mode for imaging of the subject's chest.
(Item 30)
29. Apparatus according to any of items 20 to 28, wherein the anti-scatter grid is further configured to be retractable to allow removal of the anti-scatter grid from the imaging area.
(Item 31)
29. An apparatus according to any of items 20 to 28, wherein each partition of the plurality of partitions is substantially linear.
(Item 32)
29. Apparatus according to any of items 20 to 28, wherein the anti-scatter grid has a density of at least 70 partitions / cm.
(Item 33)
29. The apparatus according to any one of items 20 to 28, wherein each partition of the plurality of partitions is a thin strip.
(Item 34)
29. An apparatus according to any of items 20 to 28, wherein the plurality of partition walls are arranged in a parallel configuration.
(Item 35)
29. Apparatus according to any of items 20 to 28, wherein the plurality of partitions are arranged in a focusing configuration, and the plurality of partitions are directed to the focal point of the x-ray source.
(Item 36)
The platform includes: a compression structure configured to compress the chest; and a fixing structure configured to fix the chest between the X-ray source and the X-ray detector. 29. Apparatus according to any of items 20 to 28, comprising at least one.

Various aspects of at least one embodiment are discussed below with reference to the accompanying figures, which are not intended to be drawn to scale. The drawings are included to provide illustration and further understanding of various aspects and embodiments, and are incorporated in and constitute a part of this specification, but are intended as a definition of the limitations of the present disclosure. is not. In the figures, each identical or nearly identical component that is illustrated in various figures is represented by a like numeral. For clarity purposes, all components may not be labeled in all figures.
FIG. 1A is a cross-sectional view illustrating imaging of a subject's chest using an embodiment of a tomosynthesis imaging device having an anti-scatter grid configured in accordance with aspects of the present invention. FIG. 1B shows the same embodiment as FIG. 1A, further illustrating the movement of the anti-scatter grid along a direction parallel to the sagittal plane of interest, according to aspects of the invention. FIG. 2A is a top view of a conventional linear anti-scatter grid. FIG. 2B is a top view of a conventional cellular anti-scatter grid. 2C is a top view of the anti-scatter grid of FIG. 1 in accordance with aspects of the present invention. 3A is a perspective view of the anti-scatter grid of FIG. 1 in accordance with aspects of the present invention. 3B is a side view illustrating the distance between adjacent partitions of the anti-scatter grid of FIG. 1 according to aspects of the present invention. 4A is a cross-sectional view of the tomosynthesis imager of FIG. 1 further illustrating a conical x-ray beam in accordance with aspects of the present invention. 4B is a front view of the tomosynthesis imaging device of FIG. 1 illustrating the center position of the X-ray source in accordance with aspects of the present invention. 4C is a front view of the tomosynthesis imaging device of FIG. 1 further illustrating the movement of the x-ray source, the mutual movement of the x-ray detector, and the anti-scatter grid according to aspects of the present invention. FIG. 5 is a perspective view of one embodiment of an apparatus for reducing X-ray scattering according to aspects of the present invention. FIG. 6 is a perspective view of another embodiment of an apparatus for reducing X-ray scattering according to aspects of the present invention. FIG. 7 is a plan view of yet another embodiment of an apparatus for reducing X-ray scattering according to aspects of the present invention. FIG. 8 depicts a system for reducing X-ray scattering within a tomosynthesis system. FIG. 9 depicts a method for reducing X-ray scattering in a tomosynthesis system.

  Anti-scatter grids are often used in radiation imaging to reduce image degradation effects of scattered radiation on the image. Stationary anti-scatter grids can cause moiré pattern artifacts, particularly problematic in digital X-ray detectors, due to interference of the anti-scatter grid pattern with the pixel pattern of the X-ray detector, for example. Thus, the resulting image exhibits moiré patterning or grid line artifacts that degrade image quality. Non-limiting examples of anti-scatter grids for use in radiographic imaging include US 2012/0170711 and US Pat. Nos. 7,418,076 and 7,715,524 (see respectively Which is incorporated herein in its entirety).

  Aspects and embodiments of the present disclosure are directed to providing x-ray scattering reduction systems and methods that also allow for the reduction or correction of moire patterns for use in 2D and 3D mammography. In some embodiments, the anti-scatter grid may move relative to the x-ray detector during x-ray exposure and blur the moire pattern. In various embodiments, the moire pattern can also be reduced using image processing techniques.

  According to one aspect of the present disclosure, it is understood that the movement of the anti-scatter grid presents unique challenges for use in tomosynthesis imaging systems that preclude the use of the anti-scatter grid for tomosynthesis imaging. For example, the movement of the anti-scatter grid must be synchronized with the X-ray exposure signal. However, in contrast to conventional 2D mammography, tomosynthesis imaging involves obtaining a plurality of X-ray projection images of the chest, each of the X-ray projection images being each of a plurality of angular displacements of the X-ray source relative to the chest. Obtained during a short X-ray exposure time. Therefore, the anti-scatter grid must travel an effective distance to reduce the moire pattern for a very short duration corresponding to the X-ray exposure of tomosynthesis imaging. Furthermore, tomosynthesis imaging systems typically impose severe spatial constraints on the distance that the anti-scatter grid can travel during imaging.

  Various aspects and embodiments presented herein address the aforementioned challenges. In various embodiments, the anti-scatter grid includes thin strips, also referred to as barriers or stacks. The septum can be made from a radiopaque material such as lead or a high x-ray absorbing material and can be separated by a gap. The gap may be made from a radiolucent material such as carbon fiber or aluminum or a low x-ray attenuation material. In contrast to conventional anti-scatter grids, the anti-scatter grid embodiments disclosed herein allow each partition of the anti-scatter grid to be in an axis substantially parallel to the coronal surface of the object during imaging. And can be configured to be positioned relative to the X-ray imaging device, and more specifically to the tomosynthesis imaging device, so as to be oriented along the length. In some embodiments, the anti-scatter grid may be configured to move along a direction substantially parallel to the sagittal plane of the object during imaging. In some embodiments, the anti-scatter grid typically has a partition density in the range of 30-50 partitions / cm, in contrast to a conventional anti-scatter grid, at least 70 partitions / cm. It may have a partition density, also referred to as linear density. Various embodiments disclosed herein are configured such that the anti-scatter grid reduces the moiré pattern in the duration, and in the resulting image, in synchronization with tomosynthesis imaging x-ray exposure. In orientation, it is possible to move a relatively short distance compared to a conventional anti-scatter grid.

  It should be understood that the method and apparatus embodiments discussed herein are not limited in application to the details of the construction and arrangement of components set forth in the following description or illustrated in the accompanying drawings. The method and apparatus may be implemented in other embodiments and may be practiced or carried out in various ways. Examples of specific implementations are provided herein for illustrative purposes only, and are not intended as limitations. In particular, acts, elements, and features discussed in connection with any one or more embodiments are not intended to be removed from a similar role in any other embodiments.

  Also, the terms and terminology used herein are for illustrative purposes and should not be considered limiting. Any reference to system or method embodiments or elements or acts herein referred to in the singular can also include embodiments including a plurality of these elements, and any embodiment or elements herein Any reference to a plurality of elements or acts may also encompass embodiments that include only a single element. As used herein, the use of “including”, “comprising”, “having”, “containing”, “involving”, and variations thereof is used Is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Reference to “or” is included as an inclusion that any term described using “or” may indicate one, two or more, and all of the terms being described. Can be interpreted.

  For convenience and clarity of illustration, it should be understood that reference numerals may be repeated between figures to indicate corresponding or similar elements or steps, where appropriate.

  Referring now to the drawings, FIG. 1A illustrates a cross-sectional side view of imaging of the chest of a subject 100 using a tomosynthesis imaging device 102 having an anti-scatter grid 104 configured in accordance with aspects of the present disclosure. In some embodiments, the tomosynthesis imaging device 102 is further described, for example, in patent documents US 7,831,296, US 2011/0216879, and US 2012/0219111 (incorporated herein by reference in its entirety). May be operable in 2D mammography mode.

  The tomosynthesis imaging device 102 includes an X-ray source 106, also referred to as an X-ray tube. The x-ray source 106 is configured to deliver an x-ray beam toward the subject's 100 chest, for example, as indicated by the line 108. In 2D mammography mode, the X-ray source can direct the X-ray beam from a fixed position during X-ray exposure. In the tomosynthesis mode, the x-ray source may move along a path, such as an arc above the chest of subject 100, as further illustrated and described below with reference to FIGS. 4A-4C. The tomosynthesis imaging device 102 further includes an x-ray detector 110 that is positioned to receive x-rays transmitted through the chest being imaged. In some embodiments, the detector may be a digital x-ray detector. For 2D mammography imaging, the X-ray detector 110 may be stationary. In tomosynthesis mode, the X-ray detector 110 moves or rotates along a reciprocal path relative to the motion of the X-ray source 106, as further illustrated and described below with reference to FIGS. 4A-4C. Thereby maintaining its orientation towards the X-ray source.

  The tomosynthesis imaging device 102 further includes a platform 112 configured to position the chest of the subject 100 between the x-ray source 106 and the x-ray detector 110. The platform 112 is positioned between the X-ray source 106 and the X-ray detector 110, and at least one of the X-ray source and X-ray detector rotates around the platform during tomosynthesis imaging of the subject's 100 chest. If so, stay stationary. The tomosynthesis imaging device 102 further includes a fixation structure 114 configured to compress and fix the chest for imaging. The chest reduces subject movement, also reduces scattering, isolates overlapping structures within the chest, makes the thickness of the chest being imaged more uniform, and provides more uniform x-ray exposure Can be squeezed. Although platform 112 and anchoring structure 114 have been described as separate elements with reference to FIG. 1A, the platform and anchoring structure can be provided as integrated elements.

  FIG. 1A further illustrates the body surface of the subject 100. 1A is in a plane parallel to the sagittal plane of the object. The sagittal plane is a longitudinal section that divides the object 100 into right and left portions. The sagittal plane is parallel to the yz plane, including the y-axis 122 and the z-axis 124, as shown in FIG. 1A. The x-axis (not shown in FIG. 1A, but further illustrated and described below with reference to FIGS. 4B and 4C) extends out of the page and is orthogonal to the yz plane. The coronal surface 126 of the object 100 is another longitudinal section that divides the object into front and back portions. A coronal surface 126, indicated by a dashed line in FIG. 1A, is parallel to the xz plane, including the z-axis 124 and the x-axis. The cross section 128 of the object 100 is a horizontal plane that divides the object into upper and lower portions. The cross section 128, shown by the dashed line in FIG. 1A, is parallel to the xy plane, including the y-axis 122 and the x-axis. The sagittal plane, the coronal plane 126, and the cross section 128 are orthogonal to each other and parallel to the yz plane, the xz plane, and the xy plane, respectively.

  Body surface references are used herein to describe the orientation and movement of the anti-scatter grid. It should be understood that the anti-scatter grid can be fixed relative to the position of the arm of the X-ray imaging device and the anti-scatter grid motion can be described based on the Cartesian coordinates of the arm that can be positioned relative to the body surface. .

  The tomosynthesis imaging device 102 includes an anti-scatter grid 104 having a plurality of partitions 116. The anti-scatter grid 104 has a partition density of at least 70 partitions / cm. The anti-scatter grid 104 is positioned between the platform 112 and the x-ray detector 110 and is configured to reduce x-rays scattered by the breast tissue from reaching the x-ray detector 110 during imaging. The The anti-scatter grid 104 is positioned relative to the tomosynthesis imaging device 102 such that each partition 116 of the plurality of partitions extends along a direction substantially parallel to the coronal surface 126 (or xz plane). In some embodiments, the plurality of septums may be exactly parallel to the coronal plane, slightly offset from the coronal plane (but generally in that plane), or some combination thereof. . For illustrative purposes, as an example, the septum closest to the patient's chest wall may be exactly parallel to the coronal plane, while the septum furthest from the chest wall may be slightly offset from the coronal plane (provided that Generally in that plane). In another embodiment, the septum closest to the patient's chest wall may be slightly offset from the coronal plane (although generally in its plane), while the septum furthest from the chest wall is exactly the coronal plane. Can be parallel. FIG. 1A shows a side view of the septum 116 illustrating the height and thickness of the septum. However, the septum 116 has a length that extends along an axis parallel to the coronal surface 126, as further illustrated and described below with reference to FIG. 3A. For chest imaging, the orientation of the septum 116 along a direction substantially parallel to the coronal surface 126 may correspond to a septum substantially parallel to the subject's 100 chest wall. The configuration of the septum extending longitudinally along a direction substantially parallel to the coronal surface 126 maximizes transmission through the anti-scatter grid during tomosynthesis imaging. In certain embodiments, the septum is focused, for example, to an x-ray source such that the septum closest to the chest wall does not have the same alignment as the septum furthest from the chest wall. In addition or alternatively, the partitions on the top surface of the anti-scatter grid 104 are substantially parallel to each other.

  FIG. 1B shows the same embodiment for imaging the chest of the subject 100, further illustrating the movement of the anti-scatter grid 104. As shown, the anti-scatter grid is moved relative to the x-ray detector 110. The anti-scatter grid 104 moves along a direction substantially parallel to the sagittal plane (or yz plane). As mentioned above, the movement of the anti-scatter grid relative to the X-ray detector can reduce the resulting moiré pattern in the image. In various embodiments, the movement of the anti-scatter grid along a direction substantially parallel to the sagittal plane maximizes grid line blur (moire pattern) and reduces grid line intensity.

  The x-ray detector 110 may be stationary during some imaging modes, but the x-ray detector maintains its orientation towards the x-ray source as the x-ray source moves during tomosynthesis imaging. Can be moved as follows. The movement of the anti-scatter grid 104 can further be coupled to the movement of the X-ray detector 110. For example, the anti-scatter grid 104 can be rigidly attached to the X-ray detector 110. Therefore, the anti-scatter grid can move with the X-ray detector as the X-ray detector moves. For example, during tomosynthesis imaging, the anti-scatter grid moves or rotates with the x-ray detector and maintains its orientation towards the focus of the x-ray source 106 while simultaneously moving relative to the x-ray detector; Moire patterns can be reduced. In various embodiments, the anti-scatter grid 104 can move with the x-ray detector 110 while the septum 116 maintains its orientation along a direction substantially parallel to the coronal surface 126. For example, the x-ray detector 110 may rotate about an axis parallel to the y-axis 122, with the anti-scatter grid 104, while the septum 116 maintains a length direction parallel to the coronal surface 126 (eg, FIG. As shown in 4C). In other embodiments, the anti-scatter grid may not move or rotate with the x-ray detector. In yet other embodiments, the anti-scatter grid may be stationary during tomosynthesis imaging. For example, the anti-scatter grid can be coupled to a stationary platform.

  Anti-scatter grid 104 is further configured to move along a second direction substantially parallel to coronal surface 126 of object 100 during imaging. In various embodiments, the anti-scatter grid is along at least one of a first direction substantially parallel to the sagittal surface of the object 100 and a second direction substantially parallel to the coronal surface 126. Can move. For example, movement of the anti-scatter grid along the x-axis, in conjunction with movement along the y-axis, allows circular and / or elliptical movement. If the septum is slightly out of parallel with the chest wall (coronal plane), circular or elliptical motion can further blur grid lines and reduce moire patterns.

  The anti-scatter grid 104 can move along a trajectory that allows for reduction of the moire pattern in the resulting image. The motion trajectory of the anti-scatter grid can be linear, circular, or elliptical. Furthermore, the anti-scatter grid 104 can move at a speed effective to reduce moire patterns during tomosynthesis imaging. The velocity profile can minimize the velocity variation of the anti-scatter grid, thereby reducing the grid lines. The velocity profile may be one of a sine wave profile and a trapezoid profile. A sinusoidal profile can simplify the motion algorithm. For example, a rotary motor as further illustrated and described below with reference to FIG. 5 can be used to provide a sinusoidal profile. The constant speed of the rotary motor shaft can produce a sinusoidal profile in the direction of the x-axis and / or the y-axis, for example. A trapezoidal profile can be more effective at blurring grid lines compared to a sinusoidal profile. However, a trapezoidal profile can be difficult to employ in a rotary motor and can instead be provided by a linear motor as further illustrated and described below with reference to FIG. The movement of the anti-scatter grid 104 causes X-ray exposure during tomosynthesis imaging so that the anti-scatter grid moves along a trajectory that allows the reduction of moire patterns during each exposure of the plurality of tomosynthesis exposures. Can be synchronized with dew.

  In some embodiments, the anti-scatter grid 104 can be retractable, either partially or completely, and / or can be removed from the imaging area between the platform 112 and the x-ray detector 110. And / or the anti-scatter grid 104 may be replaced with another grid having a different configuration. For example, the anti-scatter grid 104 can be retracted and / or disrupted outside the imaging region for operation in 2D mammography mode and returned into the imaging region for operation in tomosynthesis mode. In addition, optionally, the anti-scatter grid 104 can be used in 2D mammography mode. In general, for multi-mode mammography systems, the anti-scatter grid is in view for one mode that is either stationary or moving during exposure and / or another mode, for example, Can be out of view for 2D mammography mode, magnification mode, etc. In various embodiments, the anti-scatter grid 104 can be configured according to one or more features disclosed herein, such as the features described with reference to FIGS.

  FIG. 2A is a top view of a conventional anti-scatter grid 200 having a plurality of partitions 202. The septum 202 is linear and extends in a length direction parallel to the y-axis 122 shown in both FIGS. The x-axis 204 shown in FIG. 2A is not visible in FIG. When the anti-scatter grid 200 is used in conjunction with a conventional 2D mammography system, the partition 202 of the anti-scatter grid 200 is in contrast to the configuration of the anti-scatter grid 104 where the partition 116 extends along a direction parallel to the coronal plane. And perpendicular to the coronal surface 126.

  FIG. 2B is a top view of a conventional cellular anti-scatter grid 206 having a first series of partitions 208 and a second series of partitions 210 extending perpendicular to the first series of partitions. Septums 208 and 210 are oriented at non-zero angles with respect to x-axis 204 and y-axis 122, thereby creating a mesh pattern. Referring to FIGS. 2A and 2B, conventional anti-scatter grids 200 and 206 are typically used in 2D mammography imaging systems. However, as mentioned above, these conventional grids do not address the challenges associated with tomosynthesis imaging.

  FIG. 2C shows a top view of the anti-scatter grid 104 shown and described above with reference to FIG. FIG. 2C further illustrates the length of the septum 116. In FIG. 2C, the septum 116 is shown extending lengthwise along the direction of the x-axis 204 (the x-axis is not visible in the cross-sectional view of FIG. 1). More generally, the septum 116 may extend longitudinally along the direction of any axis substantially parallel to the coronal surface 126 (or xz plane). The anti-scatter grid may be characterized by a partition density equal to 1 / (d + t), where d is the distance between adjacent partitions and t is the partition wall thickness. The partition density of the anti-scatter grid 104 on one side is about 100 partitions / cm. In other embodiments, the partition density is typically at least 70 partitions / cm, preferably in contrast to conventional anti-scatter grids, having partition densities in the range of 30-50 partitions / cm, It can be about 100 septa / cm. A higher partition density allows the anti-scatter grid to travel a relatively short distance compared to conventional anti-scatter grids to reduce the resulting moiré pattern in the image. This typically allows the use of anti-scatter grids in tomosynthesis imaging systems that impose severe spatial constraints on the distance that the anti-scatter grid can travel during imaging. Increasing the partition wall density of the anti-scatter grid 104 has advantages for tomosynthesis imaging as described above, but increases the partition wall density and / or grid ratio defined by h / d (h is the partition wall height). , D is the distance between septums) can also result in a reduction in the primary x-rays reaching the x-ray detector, which requires delivery of an increased radiation dose to the object being imaged Please note that.

  FIG. 3A shows a perspective view of the anti-scatter grid 104 having a plurality of partitions 116 that further illustrates the orientation of the anti-scatter grid relative to the same reference coordinate system defined by the orthogonal axes x, y, and z of FIG. Show. The coronal surface 126 of FIG. 1 is parallel to the xz plane, including the x-axis 204 and the z-axis 124, and the sagittal surface of the object 100 of FIG. Including, parallel to the yz plane. Each partition 116 is a thin strip having a respective length l, height h, and thickness t. Each partition 116 is shown in FIG. 3A as extending longitudinally along a respective axis parallel to the xz plane or coronal surface 126. Adjacent partitions are separated by a distance d. The gap between the septums can include a low x-ray attenuation material. In some embodiments, the anti-scatter grid may include a support made from aluminum or another low x-ray attenuation material.

  FIG. 3B shows a side view of the anti-scatter grid 104 with the septum 116 further illustrating the distance d between adjacent septa. 3A and 3B, the partitions 116 of the anti-scatter grid 104 are shown arranged in a parallel configuration, and the partitions are parallel to each other. For example, FIG. 3A shows a plane defined by the length and height of each septum 116 parallel to the plane of the other septum. In other embodiments, the anti-scatter grid may have septa arranged in a focusing configuration, with the septa substantially focusing towards the focal point of an x-ray source, such as the x-ray source 106 of FIG. In this case, the planes defined by the height and length of the septum are not parallel to each other, but instead are slightly offset in angle to match the divergence of the X-ray beam from the X-ray source focus to the X-ray detector. Can be directed to do. The focusing of the anti-scatter grid barrier allows the passage of the main X-rays along the path originating from the focal point of the X-ray source and blocks the scattered X-rays traveling along the other paths. During tomosynthesis imaging, the anti-scatter grid with the septum arranged in a focusing configuration is moved in line with the movement of the x-ray source so that the septum remains focused towards the focal point of the x-ray source. obtain. It should be understood that an anti-scatter grid having a focusing septum can also extend lengthwise along a direction parallel to the coronal surface of the object being imaged, according to aspects of the present disclosure.

  FIG. 4A illustrates the tomosynthesis imager 102 of FIG. 1 that includes an X-ray source 106, an X-ray detector 110, a platform 112, and an anti-scatter grid 104 positioned between the platform 112 and the X-ray detector 110. FIG. FIG. 4A further illustrates a conical x-ray beam 400 emitted by the x-ray source 106 and transmitted through the compressed chest 402 (compression structure not shown in FIG. 4A). As described above, the anti-scatter grid 104 has the partition walls arranged in a focusing configuration, for example, taking into account the distance between the X-ray source and the anti-scatter grid, and the X-ray detector from the focal point of the X-ray source 106. It can be configured to match the divergence of the x-ray beam 400 to 110.

  FIG. 4B is a front view of the tomosynthesis imaging device 102 of FIGS. 1 and 4A, further illustrating the x-ray source 106 positioned above the compressed chest 402 and aligned with the central axis 404. X-ray detector 110 and anti-scatter grid 104 are oriented parallel to the xy plane (or cross section 128 in FIG. 1). The anti-scatter grid 104 has a partition wall extending in the length direction along a direction parallel to the xz plane (or the coronal surface 126 in FIG. 1). The septum can further be focused toward the focal point of the x-ray source 106. FIG. 4B further illustrates the collimator 406 of the tomosynthesis imaging device 102. A collimator 406 is positioned between the X-ray source 106 and the platform 112 and is configured to limit the X-ray beam 400 to provide only the chest 402 to be imaged, resulting in a limited X-ray beam 408. Is done. Use of the collimator 406 avoids irradiating portions of the object that are not imaged and further reduces the contribution of Compton scattered X-rays to the resulting image.

  4C is a front view of the tomosynthesis imaging device 102 of FIGS. 1, 4A, and 4B, further illustrating the movement of the X-ray source 106 and the mutual movement of the X-ray detector 110 and anti-scatter grid 104. FIG. . When the tomosynthesis imaging device 102 is operating in 2D mammography mode, the X-ray source 106 is stationary and corresponds to an X-ray source fixed position, such as a position aligned with the central axis 404 in FIG. 4B. Is obtained. When the tomosynthesis imaging device 102 operates in the tomosynthesis mode, multiple X-ray images are taken as the X-ray source 106 and X-ray detector 110 move relative to the fixed and compressed chest 402. FIG. 4C shows the x-ray source 106 positioned at an angle with respect to the central axis 404. FIG. 4C further shows that the X-ray detector 110 and anti-scatter grid 104 are rotated about the central axis 404 so that they remain directed to the X-ray source 106. The anti-scatter 104 septum may remain substantially parallel to the xz plane (or coronal surface 126) as the anti-scatter grid moves with the x-ray detector 110. In addition to the motion of the anti-scatter grid coupled to the motion of the X-ray detector 110, the anti-scatter grid 104 further includes, for example, with respect to the X-ray detector, as described and illustrated with reference to FIG. 1B. Can move. In some embodiments, the anti-scatter grid 104 may rotate with the x-ray detector 110 and translate relative to the x-ray detector. For example, the X-ray detector 110 can rotate to coincide with different angular positions of the X-ray source 106 during each X-ray exposure for tomosynthesis imaging, reducing the moire pattern. To move relative to the X-ray detector. In other embodiments, the anti-scatter grid need not move with the x-ray detector during tomosynthesis imaging. For example, the anti-scatter grid may remain stationary, move at a different speed than the x-ray detector, or move in a different direction from the x-ray detector.

  Although only a single off-axis center position 106 of the x-ray source is illustrated in FIG. Photographed every 1 ° of arc extending from −15 ° to + 15 °. In some embodiments, the imaging of image data is stopped at their respective positions after the X-ray source 106, anti-scatter grid 104, and X-ray detector 110 have moved from one position to the next. Can occur while you are. That is, at each position corresponding to the X-ray source 106, anti-scatter grid 104, and X-ray detector 110, the X-ray source 106 is excited and emits a collimated X-ray beam, and the respective image of the chest 402. Get. In other embodiments, the motion of one or all of the X-ray source 106, the X-ray detector 110, and the anti-scatter grid 104 may be continuous, and each set of image data is a continuous motion of A slight increment is accumulated, for example, over a 0.1 ° to 0.5 ° arc of motion of the X-ray source 106. Further, although FIG. 4C illustrates rotation of the X-ray detector 110 to maintain its orientation toward the X-ray source 106, in other embodiments the X-ray detector is, for example, parallel, In addition, it can move linearly at the same distance from the platform 112. In yet another embodiment, the X-ray detector 110 rotates in the same direction as the X-ray source 106. The rotation of the X-ray detector 110 is synchronized with the X-ray source 106 and is proportional to the angle. During tomosynthesis, the X-ray detector 110 may rotate at a rate of 1 / 3.5, i.e., ± 4.3 °, for an X-ray source 106 rotation of ± 15 °. When the X-ray source 106 is driven, the X-ray detector 110 follows through the gear mechanism. In other embodiments, rotation of the X-ray source 106 and X-ray detector 110 may be coordinated via a controller, as in the system described below in FIG.

  The system described herein allows movement of the anti-scatter grid relative to one or both of the x-ray source and x-ray detector. For example, referring to FIGS. 1A and 1B, anti-scatter grid 116 may move along an axis parallel to z-axis 124 (ie, closer to or farther from x-ray source 106). In another embodiment, the anti-scatter grid 116 may move along an axis parallel to the y-axis 122 (ie, closer to or farther from the patient 110). Alternatively or additionally, the anti-scatter grid 116 may move along an axis parallel to the x-axis (not shown) (ie, parallel to the patient 100). For example, pivoting about the y-axis or x-axis as depicted in FIG. 4C above is also envisioned. Rotational movement about the central axis 404 depicted in FIG. 4B can also be utilized as desired.

  Exemplary systems and structures that allow movement relative to a particular plane or axis are described in further detail below. Movement of the anti-scatter grid along an axis can show particularly desirable results when used in conjunction with tomosynthesis. Although a single motor is depicted in the examples below, multiple motors or actuators can be used in conjunction with an anti-scatter grid to move the element in any direction as required or desired for a particular application. obtain. In addition, the motor may drive a connection or other element having multiple degrees of freedom to move the anti-scatter grid as desired relative to any plane or axis defined herein. A gear system may be utilized to control the speed of movement relative to one or both of the detector and emitter.

  FIG. 5 is a perspective view of one embodiment of an apparatus 500 for reducing X-ray scattering. Apparatus 500 includes an anti-scatter grid 502 that can be configured in accordance with one or more features disclosed herein. For example, the anti-scatter grid may have a plurality of partitions, each partition extending lengthwise along a direction parallel to the xz plane (or the coronal surface 126 of FIG. 1). Apparatus 500 further includes a motor 504. In some embodiments, the motor 504 can be a stepper motor or a servo motor. The eccentric 506 is coupled to the motor 504 at a position offset from the center. Further, the anti-scatter grid 502 includes an elongated opening 508. The elongated opening 508 is elongated along a direction substantially parallel to the length of the septum. The eccentric 506 is inserted through the elongated slot 508. Since the opening 508 is elongated, at least one gap is created when the eccentric 506 is inserted through the elongated slot 508. As the eccentric 506 rotates, the anti-scatter grid 502 moves back and forth along a direction substantially parallel to the yz plane (or parallel to the sagittal plane of FIG. 1). In this case, the anti-scatter grid 502 will move back and forth along the direction of the y-axis 122. The gap created when the eccentric 506 is inserted through the elongated slot 508 prevents the anti-scatter grid from moving along the direction of the x-axis 204. However, in other embodiments, the motor 504 can be coupled to the anti-scatter grid 502 to allow movement along the x-axis 204. A motor utilizing an eccentric connected to the anti-scatter grid is oriented as desired to move the anti-scatter grid in any desired direction relative to any plane or axis described herein. Can be.

  A rotary motor, such as the motor 504 of FIG. 5, can be used to provide a sinusoidal velocity profile. In various embodiments, a constant speed of the rotary motor shaft may produce a sinusoidal profile, for example, in the x-axis and / or y-axis directions. In various embodiments, a rotary stepper motor can be a cost effective mechanism for providing a sinusoidal profile.

  In one embodiment, the anti-scatter grid 104 of FIG. 1 may be configured according to the apparatus 500 and anti-scatter grid 502 of FIG. Accordingly, the anti-scatter grid 502 can be configured to move along a first direction substantially parallel to the sagittal plane of the object 100 of FIG. It can be configured to move along two directions.

  FIG. 6 is a perspective view of another embodiment of an apparatus 600 for reducing X-ray scattering. Apparatus 600 includes an anti-scatter grid 602 that can be configured in accordance with one or more features disclosed herein. Apparatus 600 further includes a motor 604 that is coupled to the anti-scatter grid by mechanism 606. In various embodiments, the motor 604 can be a linear motor, a stepper motor, a piezoelectric motor, or a voice coil. The motor 604 may be configured to translate the anti-scatter grid back and forth along a direction such as a direction parallel to the sagittal plane of the object 100 in FIG. In various embodiments, a linear motor, such as the motor 604 of FIG. 6, can be used to provide a trapezoidal profile that can be more effective in blurring grid lines compared to a sinusoidal profile. However, linear motors can be more expensive compared to rotary motors. Regardless of the type of motor utilized, such a motor is connected to the anti-scatter grid as desired, and can be attached to any anti-scatter grid for any plane or axis described herein. It can be moved in the desired direction.

  In various embodiments, a motor (such as motor 504 of FIG. 5 or motor 604 of FIG. 6) can be configured to move the anti-scatter grid with a velocity profile that is one of a sinusoidal profile and a trapezoidal profile, and tomosynthesis. It can be synchronized with the X-ray exposure duration in imaging mode. As described above with reference to FIGS. 5 and 6, a sinusoidal profile can be easier and cost effective to implement, for example, by using a rotary motor as shown in FIG. Trapezoidal profiles can be more expensive to implement, for example, by using a linear motor as shown in FIG. However, the trapezoidal profile can more effectively reduce the moire pattern compared to the sinusoidal profile.

  FIG. 7 shows that the motor that retracts the anti-scatter grid for a mammography system, eg, an integrated multi-mode mammography system, imparts motion to the anti-scatter grid during exposure for tomosynthesis image acquisition. 1 illustrates an embodiment of the present invention that is a motor. Anti-scatter grid 700 (partition not shown) is coupled to grid carriage 702. Anti-scatter grid 700 and grid carriage 702 are coupled to motor 704. One non-limiting example of such a coupling is a lead screw 706 that is coupled to a grid carriage 702 via a nut 708. Other known mechanical arrangements for coupling the motor 704 to the grid carriage 706 can also be utilized. As discussed herein, in certain modes 708, the motor 704 can retract the anti-scatter grid 700 completely from view. Alternatively, the motor 704 can partially retract the anti-scatter grid 700 so that it is not completely within the field of view in case of exposure. In another mode 708, the motor moves the anti-scatter grid 700 during exposure for image acquisition, such as tomosynthesis image acquisition.

  FIG. 8 depicts a system for reducing x-ray scattering within tomosynthesis imaging system 800. The system includes an x-ray emitter 802, a detector 804, and an anti-scatter grid 806. Each of these configurations includes position sensors 802a, 804a, 806a, respectively. In addition, each component may be actuated (eg, moved linearly, rotatably, pivotably, etc.) by one or more actuators or motors 802b, 804b, 806b, respectively. Signals indicating position, orientation, speed of movement, etc. are sent to a controller 808 that can activate any of the three components 802, 804, 806. Thus, the controller determines the position of each component relative to one or more of the other components, sends signals to the various actuators, and moves each component as required or desired.

  FIG. 9 depicts a method 900 for reducing x-ray scattering in a tomosynthesis system. In one embodiment, the method 900 for reducing X-ray scattering comprises positioning an anti-scatter grid configured according to one or more features disclosed herein relative to an X-ray imaging device, such as a tomosynthesis imaging device. May be included. In particular, the method may include positioning an anti-scatter grid between the x-ray source and the x-ray detector of the tomosynthesis imager, eg, as shown in FIGS. 1 and 4 (operation 902). The method further includes, as illustrated and described above with reference to FIGS. 1-4, during the tomosynthesis imaging of the chest, each partition of the plurality of partitions of the anti-scatter grid each substantially parallel to the coronal plane of interest. Can be oriented longitudinally along the axis (operation 904). In some embodiments, the anti-scatter grid may have a partition density of at least 70 partitions / cm. The septum can be arranged in a parallel or focused configuration with respect to the x-ray source.

  In some embodiments, the method may further comprise performing at least one of fixation and compression of the subject's chest using, for example, a fixation or compression structure, as shown in FIG. Operation 906).

  In various embodiments, the method of reducing X-ray scattering can also include reducing the moiré pattern in the resulting image. Thus, the method of reducing X-ray scattering further couples the anti-scattering motion to that of the X-ray detector or emitter such that the anti-scatter grid moves with the X-ray detector or emitter during tomosynthesis imaging. (Act 908). When combined, the anti-scatter grid may be moved relative to one or both of the x-ray detector or the emitter (operation 910). In various embodiments, movement of the anti-scatter grid can include rotation or translation of the anti-scatter grid. In some embodiments, the method moves the anti-scatter grid along a first direction substantially parallel to the sagittal plane of the object, for example, as shown in FIG. 1B, during tomosynthesis imaging. Can include. In some embodiments, the method may include moving the anti-scatter grid in a second direction substantially parallel to the coronal plane of the object during tomosynthesis imaging. In various embodiments, the movement of the anti-scatter grid may include moving the anti-scatter grid at a speed effective to reduce moiré patterns in the resulting image. For example, the velocity profile can be one of a trapezoidal profile and a sinusoidal profile. The use of anti-scatter grids with a relatively high bulk density compared to conventional anti-scatter grids further prevents scatter while moving only a small distance within the limits of the tomosynthesis imager during each X-ray exposure. The grid will enable the moire pattern to be effectively reduced.

  In various embodiments, the x-ray imaging device can be an integrated mammography and tomosynthesis device configured to be operable in both 2D and 3D modes. In some embodiments, a method for reducing X-ray scattering can include the use of the same anti-scatter grid configured according to aspects disclosed herein for imaging in both 2D and 3D modes. . In other embodiments, the method retreats an anti-scatter grid configured according to aspects disclosed herein, or an anti-scatter grid with a conventional anti-scatter grid for imaging in 2D mammography mode. Can include switching.

  While some aspects of at least one embodiment have been described above, it should be understood that various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements are intended to be part of this disclosure, and are intended to be within the scope of this disclosure. Therefore, the foregoing description and drawings are merely examples, and the scope of the present disclosure should be determined from the proper construction of the appended claims and their equivalents.

Claims (34)

An apparatus for reducing X-ray scattering, the apparatus comprising:
A motor,
An anti-scatter grid coupled to the motor,
The anti-scatter grid has a plurality of partition walls, and the anti-scatter grid is substantially parallel to the coronal surface of the object during imaging of the object using an X-ray imaging device. Configured to be positioned with respect to the X-ray imaging device so as to extend along a parallel direction;
The motor is configured to retract the anti-scatter grid out of the field of view in a first mode of the X-ray imaging device, and the motor is in a second mode of the X-ray imaging device. The anti-scatter grid is configured to move relative to the detector within the field of view;
The detector is configured to rotate during imaging of the object in the second mode, and the anti-scatter grid is configured to image the object in the second mode. An apparatus configured to rotate with a detector in a corresponding rotational direction.   The apparatus of claim 1, wherein each partition of the plurality of partitions is substantially linear.   The apparatus of claim 1, wherein the anti-scatter grid has a density of at least 70 partitions / cm.   4. The apparatus according to claim 1 or 3, wherein each partition of the plurality of partitions is a thin strip having a length extending along a direction substantially parallel to the coronal surface of the object.   The apparatus according to claim 1 or 3, wherein the plurality of partition walls are arranged in a parallel configuration.   The apparatus according to claim 1 or 3, wherein the plurality of partitions are arranged in a focusing configuration, the plurality of partitions being directed to a focal point of the X-ray source.   The apparatus according to claim 1, wherein the X-ray imaging device is a tomosynthesis imaging device.   The apparatus of claim 7, wherein the x-ray imaging device is configured to operate in a 2D mammography mode and a 3D tomosynthesis mode.   The anti-scatter grid is further configured to move along a first direction substantially parallel to the sagittal plane of the object during imaging of the object using the X-ray imaging device. The apparatus of claim 1.   The anti-scatter grid is further configured to move along a second direction substantially parallel to the coronal plane of the object during imaging of the object using the x-ray imaging device. Item 10. The apparatus according to Item 1, 3, or 9.   The anti-scatter grid follows a trajectory effective to reduce moiré patterns in the resulting image during imaging of the object using the x-ray imaging device operating in tomosynthesis mode, and the moiré patterns The apparatus of claim 1, further configured to travel at a speed effective to reduce.   The apparatus of claim 11, wherein the anti-scatter grid is further configured to move along the trajectory during each exposure of a plurality of tomosynthesis exposures.   13. An apparatus according to claim 11 or 12, wherein the anti-scatter grid has a density of at least 70 septa / cm to limit the distance of motion required to reduce the moire pattern. The motors are stepper motors, servo motors, linear motors, is one of the voice coil and a piezoelectric motor, The device of claim 1. The motors are further configured to move the anti-scatter grid speed profile is one of a trapezoidal profile and a sine wave profile, according to claim 1. 4. An apparatus according to claim 1 or 3, wherein the anti-scatter grid is further configured to be retractable. A device configured to operate in a tomosynthesis mode for imaging of a subject's chest, the device comprising:
A motor,
An X-ray source configured to move for imaging in the tomosynthesis mode;
An X-ray detector;
A platform configured to position a chest between the x-ray source and the x-ray detector;
An anti-scatter grid disposed between the platform and the X-ray detector;
The anti-scatter grid has a plurality of partition walls, and each partition wall of the plurality of partition walls has a length extending along a direction substantially parallel to the coronal surface of the object,
The motor is configured to retract the anti-scatter grid out of view in the first mode of the device, and the motor views the anti-scatter grid in the second mode of the device. And the second mode is the tomosynthesis mode, and the second mode is the tomosynthesis mode.
The X-ray detector is configured to rotate during imaging of the object in the second mode, and the anti-scatter grid is during imaging of the object in the second mode A device configured to rotate in a corresponding rotational direction with the detector. The apparatus of claim 17 , wherein the x-ray detector is configured to move in a reciprocal direction relative to movement of the x-ray source during imaging in the tomosynthesis mode. The apparatus of claim 18 , wherein the anti-scatter grid is coupled to the x-ray detector so that the anti-scatter grid moves with the x-ray detector during imaging in the tomosynthesis mode. The apparatus of claim 17 , wherein the anti-scatter grid is configured to move along a first direction substantially parallel to the sagittal plane of the object during imaging in the tomosynthesis mode. . 21. The apparatus of claim 20 , wherein the anti-scatter grid is further configured to move along a second direction substantially parallel to the coronal plane of the object during imaging in the tomosynthesis mode. . The anti-scatter grid follows an effective trajectory to reduce the moiré pattern in the resulting image during imaging in the tomosynthesis mode, and moves at a speed effective to reduce the moiré pattern. The apparatus of claim 17 , further configured to: 23. The apparatus of claim 22 , wherein the anti-scatter grid has a density of at least 70 septa / cm to limit the distance of motion required to reduce the moire pattern. 23. The apparatus of claim 22 , wherein the anti-scatter grid is further configured to move along the trajectory during each exposure of a plurality of tomosynthesis exposures. The apparatus of claim 17 , wherein the motor is one of a stepper motor, a servo motor, a linear motor, a voice coil, and a piezoelectric motor. 26. The apparatus of claim 25 , wherein the motor is further configured to move the anti-scatter grid with a velocity profile that is one of a trapezoidal profile and a sinusoidal profile. 27. Apparatus according to any one of claims 18 to 26 , further configured to operate in a 2D mammography mode for imaging of the subject's chest. 27. Apparatus according to any one of claims 18 to 26 , wherein the anti-scatter grid is further configured to be retractable to allow the anti-scatter grid to be removed from the imaging area. . 27. The apparatus according to any one of claims 18 to 26 , wherein each partition of the plurality of partitions is substantially linear. 27. Apparatus according to any one of claims 18 to 26 , wherein the anti-scatter grid has a density of at least 70 partitions / cm. 27. The apparatus according to any one of claims 18 to 26 , wherein each partition of the plurality of partitions is a thin strip. 27. The apparatus according to any one of claims 18 to 26 , wherein the plurality of partitions are arranged in a parallel configuration. 27. The apparatus according to any one of claims 18 to 26 , wherein the plurality of partitions are arranged in a focusing configuration, and the plurality of partitions are directed to a focal point of the x-ray source. The platform includes: a compression structure configured to compress the chest; and a fixing structure configured to fix the chest between the X-ray source and the X-ray detector. 27. Apparatus according to any one of claims 18 to 26 , comprising at least one.

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